Here is the full list of all 50 Mortal Kombat Komplete Edition achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Earn 1000 Respect Points via King of the Hill Matches
Earn 2500 Respect Points via King of the Hill Matches
Gain Mastery of All Fighters
Perform every fighter's hidden finishing move
Win 10 Ranked Online Matches in a row
Comeback with under 10% health in an Online Ranked Match
Gain Mastery of 1 Fighter
Discover and fight Hidden Kombatant 3 in Arcade Ladder
Discover and fight Hidden Kombatant 1 in Arcade Ladder
Discover and fight Hidden Kombatant 2 in Arcade Ladder
Perform a Fatality with all playable fighters
Win 10 King of the Hill Matches in a row
Complete Arcade Ladder with All Fighters
Complete all Tower missions
Perform every fighter's forward and backwards throws
Complete all Test Your Might mini-game challenges
Win 100 total Online Matches
Unlock Mileena's 3rd Alternate Costume
Win Arcade Tag Ladder with robot Sektor and Cyrax
Complete all Test Your Sight mini-game challenges
Complete Arcade Ladder on max difficulty without using a continue
Unlock 100% of the Krypt
Unlock all Alternate Costumes
Get all MK Dragons in Test Your Luck
Complete all Test Your Strike mini-game challenges
Complete 100 Online Matches
Complete 200 Versus matches (online OR offline)
Successfully land every playable fighter's X-Ray attack
Win both rounds with timer running out in an Online Ranked Match
Complete Arcade Ladder without blocking (allowed to continue)
Win A Ranked Online Match without jumping
Perform 8 throws in an Online Ranked Match
Get a Flawless Victory in an Online Match
Unlock 50% of the Krypt
Discover and fight Hidden Kombatant 4 in Arcade Ladder
Complete 25 Tower missions
Complete Story Mode 100%
Unlock Hidden Fighter "Quan Chi"
Perform 1 of each type of "-ality"
Perform any fighter's hidden finishing move
Unlock Hidden Fighter "Cyber Sub-Zero"
Complete Story Mode 50%
Win an Online Match
Spill 10000 pints of blood
Perform and land a Tag Combo
Complete Arcade Ladder with Any Fighter
Perform a Fatality!
Perform a 10-hit combo with any fighter
Complete Fatality Trainer
Complete Tutorial Mode